The long-term goal of the proposed research is to provide detailed quantitative information on the mechanical behavior of the respiratory pump in normal and organically disordered speakers and to apply that information toward: (1) a comprehensive account of respiratory function in normal speech, (2) a comprehensive account of the basis of disordered speech where respiratory dysfunction is involved, and (3) the improved diagnosis and management of respiratory-based speech pathologies. The emphasis in this goal is to acquire an understanding of the control mechanisms of speech breathing physiology at primarily neurological and mechanical levels. This includes the study of how forces provided by the respiratory pump in the form of pressures and flows act upon and interact with various structures within the head and neck to generate the sounds of speech. Although the major emphasis in the original grant period was toward the study of the adult mechanism, the long-term goal is extended for the renewal application to also include the study of the newborn and the developing respiratory pump. The specific aims toward fulfillment of this broad goal are to study the following aspects of mechanical function of the respiratory pump in normal, and whenever, procedurally feasible, organically involved speakers: (1) the work of breathing for speech, (2) the influence of body posture on speech breathing mechanics, (3) the aerodynamics of upper airway function in speech, (4) the electromyographic behavior of the respiratory pump, (5) compliance of the upper airways (vocal tract), (6) laryngeal-respiratory interactions as revealed by forced-oscillation procedures, (7) peripheral-mechanical disturbances and their influence on speech breathing physiology, and (8) volume regulation in speech.